Pressure difference measuring instrument



M. WEISS PRESSURE DIFFERENCE MEASURING INSTRUMENT Filed Marh 6. 1925 Feb. 7, 1928.

Inventor: M Qx Weiss,

a/f. His Attofneg.

Patented Feb. 7, -1928. i

y V 1,658,699 y UNITED ySTATES PATENT OFFICE. i

MAX WEISS, OF BERLIN-FRIEDENAU, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, -TO YBAIIIJFY METER COMPANY, A CORPORATION OF DELAWARE.

PRESSURE DIFFERENCE MEASURING- INSTRUMENT.

`Application iled March 6, 1925, Serial No. 13,570, and in Germany June 19, 1924.

The present invention relates to instruments such as are embodied in iiow meters and the like for measuring a pressure or a pressure diiferenceand especially to such in- 5 struments of the so-termed transformer type which comprise a primary windingconnected to a source of alternating current and to suitable measuring instruments, and a second windin in the form of a closed loop i which'may e formed of a liquid such as mercury, and the resistance of which is adapted to be varied in accordance with the p pressure or pressure difference to be measured whereby the current flowing in the primary windings is varied. `The resistance of the liquid'loop is caused to vary by its level being varied and lowered in the annular chamber in which it is located. An instrument of this general type is disclosed and claimed'in the application'of Thompson and McNairy, Serial No. 632,7 59, iiled April 17,

. 1923, now Patent No. 1,560,951, Nov. 10,

The object of the invention is to provide an improved construction and arrangement in an instrument of this type, and for a consideration of what is believed to be novel and l the invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing, Fig. 1 is a sectional view, partly diagrammatic, of astr'ucture embodying the invention, and Fig. 2vis a top plan view.

-Referring tothe drawing, 1 indicates a transformer core constructed of suitable laminations and comprisingthree legs, a middle leg 2 and outer legs 3 and 4. On middle leg 2v is a primary winding 5 whichv prising a single layer of suitably insulated wire. The terminals-(Sand 7 of winding 54 are connected to a source of alternating curmmnpassages 14 and 15. Connected to passage 14 is a trailing or lower pressure pipe 16. 545 Connected to passage 15 is aleading or hlghis shown .1n the present instance as comer pressure pipe 17 which has a loop 17a and which for a portion of its length extends along parallel to chamber 13, thus forming a U-tube one leg of which comprises chamber and the other the parallel portion of pipe 17. In this U-tube is a liquid 18 such as (mercury which is a conductor of electricity. Viewed from another aspect, it will be seen that the casing structure comprises two spaced annular walls which define between them the annular chamber 13 and that the inner casing wall, defines also a central vertical passage open at its two ends and through which extends the middle leg 2 of the transformer core.

In the present instance, the construction is shown as being embodied in a iiow 'meter and to this end trailingv and leading pipes '16 and 17 are shown as being connected to a pressure diiference creating device 19 located in a conduit 20 through which the fluid to be metered flows. A known form of vpressure difference creating device usually termed a'flow nozzle. is shown in the drawing.

When the pressures in pipes 16 and 17 are equal, the liquid columns in the two legs of the U-tube stand at the same level, which may be termed the zero level and is indicated by the line 21. At this time the liquid ring which exists in ychamber 13 may be broken or almost broken so that but little if any current will be induced in it and there will be minimum current flowing in the primary winding 5 and in the indicating circuit. The ammeters 9 and 10 may be calibrated so that under this condition they read zero and the integrating meter 11 may be compensated so that it does not move.

Now when iow takes place in conduit 20, the pressure differencel creating devicecreates a pressure difference which bears a` defi- 'nite relation to the rate of flow, and this pressure -diii'erence being applied to liquid 18 through4 pipes 17 and 16 causes .the liquid to lower in -pipe 17 and rise in chamber 13, thereby building up aliquid ring of greater .cross sectional area and hence of less resistance in chamber 13. This causes more current to flow in the primary winding 5. -The flow `of current inl primary winding 5 in'- creases with increase inthe depth of the liquid in chamber 13, (i. e. with decrease in its resistance) and thus becomes Va. ,measure` of the pressure di'erence and hence of they iow through conduit 20. The measuring instruments 9, 10 and llmay be calibrated in any suitable terms. For example, they may be calibrated to read directly in terms of'flow through conduit 20.

It will be understood that the device may be used to measure' any desired pressure or pres-sure difference and for any purpose to which it may be found applicable.

'Ilreabove described arrangement has the advantage that the primary winding of the transitar-mer is located outside the annular chamber in which the liquid formingv the closhd. secondary is located and hence such li f-fdoes not c ome into physical contact the Winding. As a result of this there is danger of the liquid short circuiting turns of the primary winding or in any way adversely a'ecting such winding due to its physical contact therewith. Also, since casing 12 is independent of winding 5, it may of core 1 and winding 5 and concentric with the middle leg 2. By this arrangement-it may be turned on its vertical axis relatively to the core so thatpassages 14 and 15 may be made to face in any desired direction. This is ofassistance often ininstalling the instrument, for it enables the casing 12 to be turned tofmake passages 14 and 15 face in the direction from which the pipes 16 and 17 come.

What I claim as new andl desire to secure by Letters Patent of the United States, is:

1. In combination, an annular casing havin a U-tube of which the chamber forms at least a portion of one leg, a transformer core associated with? the casing, and a pri-u` mary winding on the core, said winding bemg outside said chamber.

. 2. In an instrument of the character described, a casing comprising two spaced annular walls which define between them anv Vtube on which said annular chamber vforms at least a portion of one leg, and a conducting liquid in. said chamber.

3. In an instrument of the character described, a casing'comprising two spaced annular walls which define between them an annular chamber closed at its upper and lower ends, and said inner annular wall deining a passage openv at its ends, a transformer core entirely outsidethe 'casing having one leg located in said passage, a pri' mary winding on said one leg, conduits connected with the upper and lower ends of said annular chamber and forming therewith a` Uftube of which said annular chamber forms at least a portion of one leg, and a conduct- 'ing liquid in said chamber.

4.-. In an instrument of the character described, the -combination of a transformen' core, a casing surrounding a leg of the core providing a vertical annular chamber closed at its lower end, a prlmary wmdmg on the lcore outside said chamber, and a tubular memberconnected to the lower end of said annular chamber land extending parallel to.

the casing whereby it forms with the chamber a U-t-ube of which the chamber yforms at least a portion of one leg. In witness whereof, I have hereunto set my hand this 13th day of February 1925.

CERTIFICATE 0F GORRECTION.

. Patent No. 1,658,699..

Granted February 7, ,Il-928, to

MAX WEISS. f

It is hereby certified that errorappear's in the ,printed vspecification ofthe above numbered patent requiring. correction as follows; Page 2, line59, claim 2, for the word "on" read "of"; and that .the said Letters Patentshouldbe 'read with this correction therein 'that the lsame may conform to the record of the ease in the Patent Office.r

Signed and sealedv this 6th day of March, A. D. .1928.

y J. Moore, l Acting Commissioner of Patente.; 

